It seems overly cynical to reduce Anne Fortier’s Juliet into a single line pitch, but since it's already been optioned for a film, chick lit meets historical fiction meets Dan Brown meets Shakespeare is presumably how her agent sold the book to Hollywood so it’ll do here. The set up is good enough to drag the reader through the first two hundred or so pages. On the death of her Auntie, American student Julie Jacobs discovers that her heritage began in Siena and stretches back as far as the real Juliet or Guilietta, who’s story was relocated and mangled until it eventually became Shakespeare’s classic about star-crossed lovers.

The novel is then split between first person reportage of Julie's adventures in Siena and a third person historical recreation of the events surround her ancestors life, meeting Romeo, falling in love and becoming separated by familial rivalry, the former impacted by the discoveries of the latter, pieced together by Julie as discovers her legacy. The vital bit of conflict is from forces that are intent on either obscuring the information or using her research project for their own nefarious purposes, as she finds herself caught between the very same families that caused misery to the original Romeo and Juliet.

There are plenty of plusses to Fortier’s book. Her characterisation is excellent. Julie is good company as she navigates Sienese society with very witty asides about her potential suitor Alessandro and the social graces she’s supposed to adopt and appreciates the irony of being connected to such a famous story. Her sister Janet, who we're told ironically played Juliet in a school production is an excellent foil, Fortier employing her mix of attractiveness and cheekiness to move to keep the story moving. The historical characters are also just the right side of cod-Shakespearean camp and the author has some fun demonstrating the differences with the play.

Siena is also recreated in prose remarkably effectively, the geography of the city lucidly drawn. This is still a tourist view of the place; as Joanna Hogg’s British film Unrelated was keen to demonstrate, Siena has been as effected by industrialisation as anywhere, dull motels and motorways just outside of the centre. There’s none of that in this book, though you can understand Fortier wanting to conjure the romantic side of Siena since it’s entirely possible that Julie would keep to relating that herself. Fortier has still clearly researched not just the history but the modern version and is keen to fit as much of that flavour into the book, albeit augmented for her own aims.

Which is rather the problem in the end. The book is five hundred pages long and I would guess over half of that is description or insight, Fortier intent on telling us about everything she has learned. I’m a slow reader at the best of times, and I'm sure there will be some readers who'll enjoy being submerged in the details of the world, but Juliet took longer for me to plough through than some literary criticism. Too often the plot halts in order to allow for this accentuation to the point that you just wish she would get on with it. We know, for example, almost every meal the Julie eats across her stay, none of which really illuminates her character, other than that she likes to try something different abroad. Don’t we all?

It doesn’t help that with the exception of the necessary relocation to Italy, Julie isn’t a particularly goal orientated, most of her “discoveries” documents passed to her, or tales told by new acquaintances, like one of those episodes of Who Do You Think You Are? which have evidently been shot on a tight schedule (cf, David Tennant). It’s left to characters like her sister to do the leg work and then report back and all too frequently when she does piece the facts together, her revelation has already been revealed in an adjacent flashback. As a modern girl, should Julie be as impotent to her own destiny as Giuletta?

In few other places have I seen the appalling position that a girl like Giulietta would have been in, a commodity to bringing union between families from birth. However interesting the contemporary scenes are, they’re rarely as entertaining or exciting as the shorter passages set in 1340 as Romeo attempts to save his Juliet from tyranny, aided by her faithful Friar Lorenzo. On more than one occasion it’s a disappointment when the contemporary passages return and we’re dragged away from this fascinating world, even if, as Fortier admits in her notes at the back, she augmented the reality of some of the characters because of the needs of the drama.

Perhaps Fortier would have been happier turning out a purer piece of histortical fiction telling the story of the original Romeo and Juliet but the publisher has suggested it required the contemporary scenes in an attempt to attract two audiences which are habitually quite distinct or make all of that accessible. Sadly it's impossible to just read the historical fiction and skim the rest; the two are inextricably linked as necessary exposition is included in the modern period and the period story lacks a satisfactory conclusion on its own terms.

Which is then mirrored in the main story. Just as the book looks like its about to become really interesting, and make the kind of genre twist that might also drag in Twilight fans too, Fortier pulls back and delivers a thuddingly conventional climax that largely undoes much of the goodwill which has developed in the meantime and delivers few proper surprises. The back of my my preview copy offers an alternate sales pitch "Shakespeare in Love meets Labyrinth". If only the latter had been referencing Frank Oz rather than Kate Mosse.

Juliet by Anne Fortier is published by Harper Collins. RRP: £7.99. ISBN: 978-0007321865